1. Field of the Invention
The present invention relates to processing of an image signal, and more particularly, to reduction of an image.
2. Description of the Prior Art
There is a need for displaying a second image within a certain image. In this case, the second image is reduced to be displayed. When these images are each composed of vertical arrays of lines consisting of dots which are arranged in a horizontal direction, decimation is performed as an image reducing method. Reduction of an image by decimation requires that decimation in the horizontal direction in each line is performed first and decimation in the vertical direction is performed next.
During decimation, aliasing may occur. If aliasing occurs, the quality of a reduced image is deteriorated. To prevent this, signals representing the image should be filtered before decimation. However, a line memory which is capable of storing data of one or more horizontal lines is necessary in order to form a vertical filter. Additional provision of such a memory demands increased costs.